4.5 SERVOPACK Overload Characteristics and Allowable Load Moment of Inertia
4
SER
VOP
ACK Specifications and Dimensional Drawings
4-13
4.5.2 Starting and Stopping Time
The motor starting time (tr) and stopping time (tf) under a constant load are calculated using the following for-
mulas. Motor viscous torque and friction torque are ignored.
Calculate the torque from the motor current using servomotor torque constant
×
motor current (effective value).
The following figure shows the motor torque and motor speed timing chart.
n
M
:
Motor speed (min
-1
)
J
M
:
Motor rotor moment of inertia (kg
x
m
2
)
J
L
:
Load converted to shaft moment of inertia (kg
x
m
2
)
T
PM
:
Instantaneous peak motor torque when combined with a SERVOPACK (N
x
m)
T
L
:
Load torque (N
x
m)
tr =
tf =
Starting time:
Stopping time:
2
π
n
M
(J
M
+ J
L
)
(T
PM
- T
L
)
60
[s]
[s]
2
π
n
M
(J
M
+ J
L
)
(T
PM
+ T
L
)
60
Motor torque
(current amplitude)
Motor speed
tr
tf
n
M
T
PM
T
L
Time
Time
T
PM
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